My advise is to start with single family or a small multi-family ground up project first but this market environment is truthfully not the time to be completing any ground up projects unless you are self performing the construction which it doesn't appear you are in a position to do.There was a recent Philadelphia  forum chain started by someone else who was contemplating ground up in a similar fashion to what you are proposing and I cautioned they would be better off buying something that was newly built and believe after conducting their own diligence realized it was too cost prohibitive at this time to build with 3rd party GC's in Philadelphia when also accounting for the interest rate environment and cost to build.

Every system you try will have flaws, or you may salivate over a feature that appears in other software.Some familiar names are mentioned frequently: Stessa, Apartments.com, RentRedi, TenantCloud, Innago, RentManager, Avail, Rentec Direct, Doorloop, etc.I recommend conducting thorough research on each app online to understand their offerings, pricing, etc.

You are well structured to use the debt snowball to pay down houses quickly, and appears from what you have written that this would be in keeping with your current strategy.  

Not to mention you will present yourself far more professionally to prospective business partners, lenders etc. who will be necessary for your growth.The next mistake you appear to be making is equating number of doors to growth.

While rental ROI appears to be attractive even after carrying costs, the 11% transfer tax when you sell seems like a turn off.

I could write a book on how to win the lottery and its the equivalent. 

If so, it appears for investment property the max ltv is 75% vs 85% for Freddie Mac, correct?

Rock solid rental while the money is in the stocks doing double duty as the principle investment as well as your down payment equivalent.  

Right now appears to be Rockies and coastal Texas.

I’d love to hear how things are going and if you’ve noticed any difference in responses based on the sign’s appearance.